Apparatus and process for the treatment of spent fuel

ABSTRACT

Apparatus for shearing into sections or fragments, the tubes containing nuclear fuel of combustion elements, and which are secured together by lateral, longitudinally-spaced tie rods or bands. After removal of the inert ends with which each element is commonly provided, the bundle of tubes, sans ends, is moved longitudinally by steps of 20 to 30 mm each, into a shearing apparatus wherein after each step the bundle of tubes is clamped to a fixed stop or surface and the projecting ends are sheared off by a reciprocating shearing tool to thus form a number of fragments of tube and fuel each. In the prior art when two successive shearing cuts were on opposite sides respectively, of a tie band, the band still held the cut fragments together in a unitary mass of excessive size, capable of clogging the pipes leading to the tank in which the fuel or the metal of the tubes is dissolved. To obviate that disadvantage the present invention incorporates into the reciprocating shearing tool, a shearing tooth projection fixed therewith and which is spaced ahead of the shearing edge of the tool in the direction of the working stroke. The construction is such that when a tie rod or band is advanced into position to be sheared off on the next stroke of the shearing tool, the projection first engages and shears the band to thus allow the subsequently-sheared fragments of fuel and tubes to disintegrate or separate as the tool completes its shearing stroke.

United States Patent [191 Cherel [451 Mar. 27, 1973 [54] APPARATUS ANDPROCESS FOR THE TREATMENT OF SPENT FUEL [75] Inventor: Guy Henry ACherel, Bougival,

' France [73] Assignee: Saint-Gobain Techniques Nouvellas,

Courbevoie, France [22] Filed: Feb. 25, 1970 [21] Appl. No.: 13,946

[52] US. Cl. ..83/278, 83/282, 83/390, 83/622, 83/636, 83/925 R [51]Int. Cl ..B23d 15/04, B23d 35/00 [58] Field of Search ..83/277, 282,390, 622, 636, 83/694, 697, 925 R, 683

[56] References Cited UNITED STATES PATENTS 3,122,038 2/l964 Juras..83/622 X Primary Examiner-James M. Meister Attorney-John L. SeymourABSTRACT Apparatus for shearing into sections or fragments, the

tubes containing nuclear fuel of combustion elements, and which aresecured together by lateral, longitudinally-spaced tie rods or bands.After removal of the inert ends with which each element is commonlyprovided, the bundle of tubes, sans ends, is moved longitudinally bysteps of 20 to 30 mm each, into a shearing apparatus wherein after eachstep the bundle of tubes is clamped to a fixed stop or surface and theprojecting ends are sheared off by a reciprocating shearing tool to thusform a number of fragments of tube and fuel each. In the prior art whentwo successive shearing cuts were on opposite sides respectively, of atie band, the band still held the cut fragments together in a unitarymass of excessive size, capable of clogging the pipes leading to thetank in which the fuel or the metal of the tubes is dissolved. Toobviate that disadvantage the present invention incorporates into thereciprocating shearing tool, a shearing tooth projection fixed therewithand which is spaced ahead of the shearing edge of the tool in thedirection of the working stroke. The construction is such that when atie rod or band is advanced into position to be sheared ofi on the nextstroke of the shearing tool, the projection first engages and shears theband to thus allow the subsequently-sheared fragments of fuel and tubesto disintegrate or separate as the tool completes its shearing stroke.

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GUY PLCHEREL BY gw M}/ 4 AUG NEYS PATENTEDNARZY ma SHEET 13UF 13INVENTOR GUY MHEREL ATTORiEYS APPARATUS AND PROCESS FOR THE TREATMENT OFSPENT FUEL In order to improve heat transfer in atomic piles, it hasbecome necessary to fabricate combustible elements consisting of lowcross-section cartridges, e.g. on the order of one square centimeter, oreven a cartridge having complex cross-section, having for example, anexternal sheath and an internal sheath designed to'be in contact with acooling medium. Thus, it is convenient to use cartridges having adiameter on the order of one centimeter, filled with combustible nuclearpowder made of natural or enriched uranium oxide, and cartridges whoseouter and inner casings enclose between them a nuclear combustiblematerial made of a metal or a fissionable alloy.

After remaining in the piles, the irradiated elements must be treated,in order to restore a predetermined purity to the combustible nuclearmaterial and recover fission products having commercial value. Since itis practically impossible to extract this combustible material from thesheath or cartridge by mechanical means, a chemical separation processis generally employed, in which the cartridges or nuclear combustiblematerial is selectively dissolved in a suitable bath present in adissolver, or a battery of dissolvers. For example, this bath may benitric acid when the stainless steel or zirconium alloy cartridgescontain a natural or enriched uranium oxide powder, or may even besodium hydroxide when the aluminum or magnesium alloy casings enclosebetween them, uranium or one of its alloys. It is, nevertheless,essential to supply the cartridges as sections or fragments, in order toallow the bath to make contact with the combustible material, as well asto reduce the size of the dissolver bath.

Since an element consists of, in addition to cartridges connected bylateral tie rods in a bundle comprising the element component, two inertends designed to ensure emplacement in the atomic pile, we begin bysimultaneously or successively removing these ends in a mechanical saw,the cartridges making up the body of the element remaininginterconnected in the bundle, due to the lateral tie rods. This bundleis then fed to a shearing apparatus having a unit connected to adissolver or series of dissolvers, by means of a series of connectedpipes. The apparatus comprises a hold-down plate and a tool convenientlyactivated by jacks and mounted on the body of the shears, in order topermit them to slide in a predetermined direction, a stop attached tothe shears and a feeding device serving to cause the cartridge bundle totravel step by step a predetermined path, e.g. -30 mm. It should benoted, that in prior art shears, the tool has a stepped ramp inclined tothe above-mentioned direction of slide and bordered by a faceplane-situated with respect to the hold-down clamp.

Once the cartridge bundle comprising the element is pressed between thehold-down plate and the stop, the tool, activated by the jack, cuts thecartridges into sections or fragments, these sections then falling viathe connecting pipe-line system into the dissolver.

It is important to note, however, that when the tool cuts the cartridgebundle at locations in front of and behind a lateral tie rod, as well asat the location of this tie rod, said tie rod continues to interconnectthe cartridge sections lying between those locations and thus results ina formation of an essentially unitary mass capable of obstructing thedissolver or its connecting pipe-line system. Moreover, if the dissolverconsists of a conveyor passing into the bath of corrosive liquid, theabove-mentioned mass may be thereby removed from the bath before thenuclear material initially forming a part thereof, has been completelydissolved.

These disadvantages are further aggravated if it is desired tofragmentize an element whose cartridge bundle is surrounded by a sleevebecause each time the tool cuts into this jacket it forms a ringsurrounding the cartridge section.

It has been found that suitable processing equipment designed to employthe above-mentioned chemical process for separating these elementsshould embody, in addition to a mechanical saw and a conventionalshears, a device for separating the cartridge bundle from the sleeve,after removal of the inert ends of the element in the mechanical saw.

The present invention is designed to obviate the aforementioneddisadvantages.

Its object is a shearing apparatus, characterized essentially by thefact that the face of the tool located opposite the hold-down plateconsists of at least one projecting and one concave part, separated fromeach other by a distance greater than that of the each individual stepby which the feed device causes the element to travel into the shears.

The projecting part of the invention tool permits it to cut into thebody of the combustible element to a depth greater than the path overwhich the feed device travels. This means, that when the tool cuts theelement in front of and behind a lateral tie rod, or even at thelocation of a tie rod, said tie rod will be separated into at least twofragments, in the same way as the aforementioned mass of cartridgefragments. The cartridge fragments otherwise encircled and boundtogether by the tie rod, are thus released for disintegration intodiscrete pieces.

Similarly, the present invention shear tool permits separation of thesleeve ring cut in the body of the element, into at least two fragments,when its cartridge bundle is surrounded by a jacket.

Thus, danger of obstructing the dissolvers or their pipe-line systemsextending from the shears is eliminated, as well as the danger ofincomplete dissolution of combustible nuclear material or cartridgeswhen the present invention shear tool has a predetermined number ofprojecting parts as aforesaid.

The present invention also covers a processing installation comprising amechanical saw, a shears as described above and a dissolver filled witha corrosive liquid bath. This kind of installation, in effect, permitsapplication of the aforementioned chemical separation process consistingof selectively dissolving the cartridges or combustible nuclear materialin a corrosive liquid bath present in the dissolver as well as toelements devoid of jackets or elements having a jacket surrounding thecartridge bundle, without the necessity of adding a disassembling deviceto the mechanical saw and the invention shears.

The invention will become clear to those skilled in the art, after astudy of the following detailed description, in connection with theaccompanying drawing wherein:

FIG. 1 is a view of one combustible element with parts removed todisclose the tubes and the tie rods connecting them;

FIG. 1a is a detail view showing to an enlarged scale a longitudinalsection of one of the tubes;

FIG. 2 is a view generally corresponding to FIG. 1, showing acombustible element equipped with a jacket;

FIG. 3 is a schematic plan view of a conventional or prior artarrangement of an installation for handling, preliminarily treating, andtransporting the elements into the shearing apparatus;

FIG. 4 is a plan view to a scale enlarged over FIG. 3, of theconventional shearing apparatus identified at 13, FIG. 3, parts beingbroken away to illustrate mechanism otherwise obscured;

FIG. 5 is a detail sectional view to an enlarged scale, of parts of FIG.4, taken in a plane identified by line 5 5, FIG. 4;

FIG. 6 shows a conventional cutting tool having two reverse inclinedsloped steps;

FIG. 7 shows another shears having two interchangeable inclined slopedsteps;

FIG. 8 is a plan view partly in section, taken in a plane identified byline 8 8, FIG. 9, of shearing apparatus embodying the invention;

FIG. 9 is a sectional view with parts removed, and taken in a planeidentified by line 9 9, FIG. 8;

FIG. 10 shows an elevation of the invention shears;

FIG. 11 is a detail view to a scale enlarged over FIG. 10, of means forreleasably and detachably securing one tooth in place;

FIG. 12 is an elevation of a variant of the element shown in FIG. 10;

FIG. 13 shows a first variation of the device of FIG.

FIG. 14 shows a second variation of the device of FIG. 9;

FIG. 15 represents a third variation of the device shown in FIG. 9;

FIG. 16 is a diagrammatic view illustrating operation of the deviceaccording to FIGS. 8, 9, 13 or 14;

FIG. 17 is a partly plane, partly cross-sectional view along line 17-17ofFIG. 18;

FIG. 18 is a cross-sectional view along line 18-18 of FIG. 17;

FIG. 19 is a cross-sectional view along line 19-19 of FIG. 18;

FIG. 20 shows some of the bars attached to the tool and the shears stopillustrated in FIG. 18;

FIG. 21 shows a variant of the tool and the stop of FIG. 18;

FIG. 22 illustrates a variant of the device of FIG. 19;

FIG. 23 is a cross-sectional view along line 23-23 of FIG. 22;

F I6. 24 is a variant of the device of FIG. 23;

FIG. 25 shows a first variant of the element of FIG. 18;

FIG. 26 illustrates a second variant of the element of FIG. 18;

FIG. 27 is a detail plan view, partly in section, of mechanism forfeeding each nuclear element step by step into the shearing apparatus asschematically shown upon FIG. 4, and

FIG. 28 is a detail plan view, partly in section, with cover partsremoved, of shearing apparatus embodying the invention.

With reference to FIG. I of the drawings, 1 identifies generally acombustible element consisting of two inert ends 2 and a component 3comprising one or more cartridges 5 with combustible nuclear matter 4,see FIG. 1a, connected in a bundle by means of lateral tie rods 6.Component 3 and inert ends 2 are interconnected by means of longitudinaltie rods 7 consisting, if desired, of a suitable number of cartridges 5.These cartridges, made of stainless steel, for example, or of azirconium alloy called Zircaloy may contain a natural or enricheduranium oxide combustible powder, used preferably in the form ofpellets; however, it is also possible to employ cartridges having anexternal jacket 5a (FIG. 1A) and an internal jacket 5b, preferably ofaluminum, magnesium or magnesium alloy, these jackets enclosing betweenthem a metal or combustible alloy tube 4 made of uranium or uraniumalloy, for example.

In FIG. 2, the connection between component 3 and inert ends 2 issimultaneously provided by jacket 8, usually pierced by holes 8a andproviding a tubular tie rod and a longitudinal tie rod 7 and cartridges5.

When it is desirable to remove combustible nuclear material from thecartridges, successive or simultaneous cutting of inert ends 2 iscommenced, in order to remove component 3 containing the combustiblenuclear material. This component is then cut into bits in shears 9 (FIG.3), these bits being then transported to the corrosive liquid bath. Thecorrosive liquid may be nitric acid, supplemented by hydrofluoric acid,if desired, when natural or enriched uranium oxide is encased instainless steel or Zircaloy cartridges, which are almost unaffected bynitric acid. On the other hand, sodium hydroxide solution may beemployed when it is desirable to dissolve aluminum, magnesium ormagnesium alloy cartridges containing a bar or tube of uranium alloy,which is insoluble in this solution.

It should be noted, that in the first case, it is essential to cut thecartridges into sections, so that nitric acid comes into contact withthe combustible powder. In the second case, it is also desirable to feedthe cartridges in sections, in order to reduce the volume of the sodiumhydroxide bath.

The processing equipment in which the aforementioned operations areconducted consists of a cell 10 (FIG. 3), surrounded by biologicalprotection chamber 11 and containing a mechanical saw 12 and shears 9connected to magazine 13. Handling equipment, in itself well-known andnot shown for that reason, is used to transport combustible elements 1to mechanical saw 12, in order to remove inert ends 2 (FIGS. 1 and 2)from component 3. This component is then sent to magazine 13 of shears 9by means of handling device 14, comprising, for example, a mechanicalhoist l5 and loading platform 20. It should be noted that the platformor magazine is equipped with a feed device 21 (FIG. 4) serving to move(Arrow F) element component 3 along a predetermined path, step by stepthrough a distance of 20 to 30 mm each. This feed device is of a typewell-known in itself and for this reason has been summarily representedas a ram 22, driven by motor 23.

Again in this FIG. 4, it is apparent that shears 9 connected to chamber11 comprises a component 9a, the top of which is closed by cover 24connected by appropriate means 25 and its bottom part by base 26,

where there is a discharge outlet 27 connected to a dissolver or batteryof dissolvers 28 via pipeline system 28a. Inside shears component 9a,there is a sliding tool 29 and a hold-down plate 34) connected to eachother and to fixed shears stop 31. The tool has a plane face 29a locatedopposite the hold-down plate and is terminated by at least one inclinedstepped ramp 35 (FIGS. 5., 6 and 7), and another face 2% locatedopposite shears component 9a, rollers 32 being advantageously interposedbetween this component, the tool and the hold-down plate. Stop 311 alsohas a plane face 31a arranged on the extension of plane face 29a of thetool, and a face 3112 connected to the hold-down plate. Jacks 33 and 34serve to activate tool 29 and hold-down plate 30; these jacks,preferably hydraulic, are capable of developing 250 and 60 tonsrespectively when the combustible elements have a cross-section on theorder of 200-250 mm. Moreover, all these values are given forillustrative purposes and are in no way limiting.

FIG. 5 shows a conventional type of tool 29 having steps distributedalong a single inclined ramp 35. This ramp is arranged at the bottom ofthe tool, in order to facilitate dropping combustible nuclear materialinto discharge outlet 27, roller carriages 36and 37 being interposedbetween tool 29, base 26 and cover 24 of the shears, to permit slidingthe device into the shears.

It should be noted that machining work on and the replacement of thetool are simultaneously and advantageously facilitated by designing itin the form of blade holder 38 and blade 40, to which plane face 29a(FIG. 4), terminated along inclined ramp 35, is secured. This blade,resting on stop 38a of the blade holder and having gripper units 40a,preferably comprising a tapped hole, has, for example, one or moremortises 40b, where blade holder tenons 38b are engaged. Similarly, stop31 may consist of a bushing 41 attached to shears component 9a and abushing 42 resting on stop 41a attached to the bushing holder, tenons41b being used in the bushing support being engaged by mortises 42a usedin the bushing. Premature displacements of blade 40 in the blade holderand bushing 42 having gripper units 42b similar to components 40a areavoided, for example, thanks to carriage 36 and protrusion 43 of cover24.

When it is desired to replace blade 40 and bushing 42, we start bydrawing back cover 24 and carriage 36 with the help of a handlingdevice, for example (not shown), with which the treatment cells aregenerally rigged. This handling device is then reemployed to screw thethreaded rods (not shown) into holes 40a and 42b of the blade andbushing, in order to lift them out of the shears.

In one construction variant (FIG. 6), tool 29 or blade 40 have twoinclined ramps 35 and 35a.

In another variant (FIG. 7), the steps are distributed over twoparallel, symmetrically arranged ramps 35 and 35b, in the same way asmortise 4%, with respect to a center 44, the presence of a casing 45,also assembled on blade holder 38 by means of a tenon and mortisecombination (no reference), thus permitting, as in the case of the toolsin FIGS. 5 and 6, the assembly or removal of blade 40, and replacementof ramp 35 by ramp 35b.

The above-described shears operates as follows:

Component 3 is moved (Arrow F) by feed device 21 into magazine 13, untilthe forward end of this component travels a distance p beyond plane face29a of the tool, the rear end of the component being in'contact with ram22. By starting jack 34 (Arrow G), cartridges 5 of combustible materialare pressed one after the other between hold-down plate 35) and face 31bof stop 31. Cartridges 5 are then cut by tool 29, driven by jack 33,into sections that are collected in the dissolver or battery ofdissolvers 28 connected to discharge outlet 27.

Jacks 33 and 34 now slide tool 29 and hold-down plate 30 in retractionas indicated by Arrow H, component 3 being moved forward again (Arrow F)by device 21 over a distance p. As mentioned above, cartridges 5 arethen pressed between hold-down plate 30 and stop 31 and then cut by tool29.

All the aforementioned operations can be and usually are automatic,jacks 33 and 34 and motor unit 23 being driven as shown schematically bythe dotted lines by means of governor 45, which needs no description,since it lies outside the general scope of the invention.

On the other hand, it is important to note that the presence of alateral tie rod 6 (FIG. ll) prevents cartridge sections from detachingfrom one another. When tool 29 actually begins to cut the combustibleelement in front of and behind a transverse tie rod or even at thelocation of this tie rod the latter continues to hold the cartridgesections together, thus forming a mass having dimensions similar tothose of section 3a (FIG. 5) of a combustible element after compressionbetween hold-down plate 30 and stop 31. A mass of this type may obstructdissolver 28 or pipe-line 28a connecting shears discharge line 27 todissolver 28. Furthermore, if this dissolver has a conveyor (not shown)traveling into a liquid corrosive bath designed to dissolve cartridges 5or combustible nuclear material 4, this mass may leave the bath withoutcompletely dissolving the combustible nuclear material.

The aforementioned drawbacks are still further aggravated when it isdesired to use shears 9 to cut up component 3 of a combustible elementbelonging to the type shown in FIG. 2. In this case, component 3 isstill surrounded by jacket 8 after removing inert ends 2 of the elementin saw unit 16. When jack unit 34 commences to press cartridges 5between hold-down plate 30 and stop 31, this jack also compresses jacket8 against cartridges 5. The result is that every time tool 29 is pushedforward by jack 33 and begins to cut into component 3, a mass is formedconsisting of a jacket annulus around the cartridge sections.Consequently, the processing equipment (FIG. 3) should have adisassembling device 46 to remove cartridge bundle 5 from jacket 8,transportation of component 3 between machine 12, disassembly device 436and loading platform 36 being achieved, for example, by hoist 115. Inany event, it should be noted that the disassembly device will notremove lateral tie rods 6 from component 3.

We shall now describe an invention shears and demonstrate how theabove-mentioned drawbacks can be eliminated.

In one of its embodiments (FIGS. 8, 9 and I5), shears 29 has, apart fromplane face 29a, terminated by at least one stepped inclined ramp 35,another plane face 290 having one or more projections 47 with edge 470,the distances separating face 29a and 29c and edge 47a of the projectionor projections having the same value P greater than the p traveled whenram 22 impels component 3 when device 21 (FIG. 4) is operating. Thereference 29a makes it possible, therefore, to designate the plane facebordering inclined ramp 35 and edge 47a of the tooth or teeth 47 at thesame time, this edge and this plane face forming on the tool, partsprojecting with respect to the hollow part of this tool comprising planeface 290.

The shears shown in FIGS. 8 and 9 operate as follows:

As mentioned above, component 3 is moved into magazine 13 (FIG. 4), sothat the front end of this component travels a distance p in thedirection of Arrow F past plane face 29a of the tool, the rear end ofthe component being in contact with ram 22. Operation of jack 34 thenpermits, as described above, cartridges 5 with or without lateral tierod 6 (FIG. 8) or jacket 8 (FIG. 9) to be pressed between hold-downplate 30 and stop 31; but when jack 33 (Arrow G) is started, projection47 begins to dig a cut 48, indicated in summary fashion in FIG. 9cartridge bundle 5 and in lateral tie rod 6 (FIG. 8) or in jacket 8(FIG. 9). Tool 29 continues to advance in the direction of Arrow G, thusallowing cartridges 5 to be cut into sections and, if necessary, lateraltie rod 6 and jacket 8, already separated into two parts by cut 48 madeby projection 47. The result is, that when the two parts of the tie rodand jacket squeeze against sections of cartridges 5, the two masses 3a(FIG. 9) of resulting sections have dimensions less than section 3a(FIG. 5) of the front end of the element after compression betweenhold-down plate 30 and stop 31. g

In the embodiment shown in FIGS. 8 and 9 of the drawings, theaforementioned projection is formed by free end 47a, preferablyrectangular, of a tooth 47, whose other end 47b, set in preferablyrectangular hole 49 drilled in tool 29', is immobilized by one or morescrews 50.

In the FIG. 10 variant, tool 29 consists of two teeth, whose ends 47bare set in recesses 49 made in tool 29, immobilization of these teethbeing assured by means of bar 51, fitted with screws 50 and fastened totool 29 by appropriate means 52, e.g.studs and nuts, as shown in thedrawing. It should be noted that these screws have a knurled knob ontheir free end 50a (FIG. 11) and a threaded section 50b of screwdiameter d, connected to tool 29 (FIG. 8) or in bar 51 of this tool(FIGS. 10 and 11), where a corresponding thread has been tapped, theother end 50c of this thread being preferably cylindrical and having adiameter d, less than d. In case of excessive tightening of teeth 47,this prevents crushing the thread of screw 50 and damaging the thread ofthe tool or bar when screw 50 is removed.

In another variant (F IG. 12), too] 29 consists of three teeth 47, sothat the masses of cartridge sections formed during the cuttingoperation on the element have smaller dimensions than when the tool hasa single tooth (FIG. 9). Moreover, according to the invention, apredetermined number of teeth, exceeding three, can be attached to thistool, in order still further to reduce the dimensions of the masses ofcartridge sections obtained from the shears; but these methods ofattachment, shown in FIGS. 9, 10 and 12, are difficult to realize, theincreased number of teeth actually resulting in increased number ofholes or recesses 49 in the tool and reducing cross-section of teeth 47,thus seriously weakening them.

This disadvantage is overcome, however, by equipping the tool with holes49 located in several planes perpendicular to the direction of toolslide indicated by Arrows G and H. These holes are, for example,arranged parallel to single ramp 35 (FIG. 13) of blade 40, or evenstaggered, as shown in FIG. 14, blade 40 thus having, if desired, twoinclined stepped ramps 35 and 35a. Attachment of each tooth 47 isensured by a respective screw 50 (FIG. 14) by sinking the teeth in underpressure, electronic bombardment (FIG. 13), etc. It should be noted,that in the last two cases mentioned, end 47b of teeth 47 and holes 49are preferably cylindrical.

These holes may also be truncated (FIG. 15), as well as end 47b of teeth47, the locking of these teeth being ensured by nut 53 screwed onthreaded stud 47c joined to 47b.

Whatever the method adopted for attaching these teeth, it is,nevertheless, convenient to use a tool comprising a blade holder 38, towhich tenons 38b (FIG. 8) or mortises 380 are attached (FIG. 15) and asupport 54, the bottom of which rests on stop 380 (FIG. 9). This supporthas a side 55, where mortises 54a(FIG. 8) or tenons 54b (FIG. 15) areformed, the latter joining with tenons 38b or mortises 38c, and an upperpart having knob 540 (FIG. 8) and preferably a tapped hole. The otherside 56 of this support has a part 56a capable of extending face 29a ofblade 40 and another part comprising plane face 29c of the tool to whichteeth 47 and blade 40 are attached. The two parts 56a and 29c of thissupport are connected along a surface 56b, to which blade 40 isattached, attachment of this blade to support 54 being achieved bysuitable means 57, e.g. brazing (FIG. 9), screws (FIG. 13), etc.

Actually, it is unnecessary to mount blade 40 on support 54 by means ofthe mortise and tenon assembly similar to that used in the conventionalembodiment shown in FIG. 4, the raising of the support equipped withteeth 47 and blade 40 which are particularly susceptible to wear can beaccomplished, for example, once lid 24 and carriage 36 have beendisassembled by the aforementioned handling device by attaching athreaded shaft (not shown) in hole 54c.

It is well to note, however, that when blade 40 consists of two parallelramps 35 and 35b (FIG. 12) symmetrical with respect to center 44,attachment device 57, preferably consisting of screws, should beremovable and symmetrical with respect to center 44, so that the bladecan return and ramp 35b can be used when blade 35 is in use.

Moreover, preliminary tests have shown that formation of the groove orgrooves 48 is improved when stop 31 or bushing 42 have on their face 31bone or more notches 60 (FIGS. 8 and 9) situated on the extension of theprojection or projections 47a along the direction of Arrow G, thesenotches being preferably made by fraising or milling. Activation ofhold-down plate 30 results in pressing cartridges 5 and tie rod 6 (FIG.8) or jacket 8 against stop 31 or bushing 42, thus marrying (FIG.

l6) notches 60 to the tie rod or to the jacket, or the tie rod and thejacket. When the tool is now activated in the direction of Arrow G,projections 47 of the tool come opposite notches 60, then pass them,thus removing parts of the jacket and tie rod that might still jamgrooves 48. Consequently, the invention shears ensures division of thecut part of component 3 into a number of cartridge section pieces 3agreater than the number of projections or teeth on the tool.

In one variant (FIG. 17), tool 29 has projecting parts 47a on whichabove-mentioned face 29a is reduced separated by grooves 61 having abase or hollow part located on face 296, and for this reason designatedby the same reference, the projecting parts and the bottoms of thegrooves terminating along ramp 35 (FIG. 18) or along ramps 35 and 3512(FIG. 21). Stop 31 also has projecting parts 62 separated by grooves 63having a base situated on face 31a, and for this reason designated bythe same reference, these grooves and projecting parts 62 being arrangedrespectively in the extension of projecting parts 47a and grooves 61 ofthe tool. The result is, that when the tool is slid in the direction ofArrow G, projecting parts of the tool and stop penetrate the grooves ofthis stop and this tool.

We shall now describe the operation of the invention shears shown inFIGS. 17 to 26, by assuming that component 3 is pressed betweenhold-down plate 30 and stop 31, after this component has moved (ArrowF), due to the action of feed device 21 (FIG. 4), the front end of thiscomponent having traveled a distance p beyond projections 47a.

When the tool is advanced in the direction of Arrow G, these projectionssink into grooves 48 (FIG. 18) of depth p at the front end of component3, bottom 29c of grooves 61 exerting no effect. Tie rod and jacketportions of the cartridges first occupy the places in the grooves, aredriven into grooves 63 of stop 31, after having been separated from thiscomponent when projecting parts of the tool and stop penetrate thegrooves of this stop and tool. Continued tool advance in the directionof Arrow G then permits expulsion of tie rod and jacket cartridge partsfrom stop 31 and causes them to fall through discharge outlet 27 intothe dissolver or battery of dissolvers 28 (FIG. 4).

Tool and hold-down plate are now slid in the direction of Arrow H, thecomponent being advanced again (Arrow F) a distance p by device 21,thenpressed between stop 31 and hold-down plate 30. Progression of thetool in the direction of Arrow G thus permits it to reach the bottom ofgrooves 48 and cut parts 3a of the components separated by thesegrooves, by means of bottom 290 of grooves 61, if distance P is lessthan twice distance p.

If this is not the case, component 3 is advanced (Arrow F) as many timesas it is necessary for base 290 to be able to cut parts 30, thisadvancing operation being preceded by the aforementioned movement ofholddown plate and tool in the direction of Arrow I-I.

As a result of the above, the invention tool can slash component 3 intopieces having diameters smaller than grooves 61, tie rod 6 and jacket 8being pinched and then cut between the tool and stop 31, as the toolmoves in the direction of Arrow G. This obviates formation of cartridgesection pieces capable of plugging dissolver 28 (FIG. 4) or pipe-linesystem 28a and hinlltl dering dissolution of combustible nuclearmaterial or the cartridges.

As seen in FIG. 17, grooves 61 can be rough-hewn by hammering face 29aof shear tool 29 and then machining with a fraise, grinding wheel, orcircular tool 58, thus giving shears tool 29 an appropriate hardeningtreatment. In this case, contrary to ramp 35 grooves 61 have a roundedpart 61a, preferably fitting a recess 2% in the hold-down plate andactually helping to remove, when necessary, fragments of combustibleelement material from the tool.

Similarly, grooves 63 can be rough-hewn by hammering on face 31c of thestop located on the extension of bottom 290 of grooves 61 and hence, ata distance P from face 31a of this stop. Grooves 63 are then milled withtool 58 or the like, the stop thus receiving a suitable hardeningtreatment. It should be mentioned that the rough-hewing and machining ofthese grooves are facilitated by attaching the stop to the inside ofcomponent 9a by a weld 31d, swaging, etc.

In a first variant (FIGS. 18-21), the part of the tool situated oppositethe hold-down plate 30 and the stop 31 has a slot 64, consisting ofwalls 64a, 64b, 64c and bottom 29d. Steel bars 65 and 66, preferablystainless, and having two thicknesses, whose difference is equal toabove-mentioned distance P, one bar 65 extending along at least one bar66 and vice versa, are brazed to these tool walls and bottom.Furthermore, one of ends 65a, 66a of these bars touches wall 64d of slot64, the other ends 65b, 66b of these bars constituting inclined ramp 35(FIG. 18) or inclined ramps 35, 35a (FIG. 21).

The result is, that a tool assembled in this manner and v in accordancewith the invention has a least one inclined ramp 35, projecting parts47a consisting of bars 65 and grooves whose bottom is made up of bars66. A slot 67, comprising walls 67a, 67b, 67c and a bottom 31d, may bemade in face 31b of the stop and in that part of the stop adjacent tothis face. Steel bars 68 and 69, preferably stainless, and having twothicknesses, whose difference is equal to the difference P, one bar 68extending along at least one bar 69 and vice versa, are brazed to thesetool walls and bottom. Furthermore, one of ends 68a, 69a of these barstouches wall 67a of slot 67, the other ends 68b and 69b of these barsextending hold-down plate face 31b. An invention stop assembled in thismanner comprises projecting parts 62 formed by bars 68 and grooves 63,whose bottom 31a is made up of bars 69.

It should be noted that the sections of bars 65 and 68, as well as thoseof bars 66 and 69, may be identical, but width of these latter barsshould be greater than bars 65 and 68, in order to maintain interplaybetween tool and stop.

In a second variant (FIG. 21), screws 70 serve to fix on the tool andstop, bars 65, 66, 68 and 69, comprising here a component made ofordinary steel, where screws 70 pass through, and ends 65a, 65b, 66a,66b, 68a, 68b, 69a and 6917 made of a material harder than ordinarysteel, e.g. tool steel or metal carbide. Used bars can be replaced andbars also turned end-on-end, in order to use end 65a, 66a, 68a and 69awhen ends 65b become dull after prolonged use.

The same applies when tool and stop bars have tenons 71, 72, 73 and 74working together with mortises '75, 76, 77 and 78 incorporated in thetool and stop. As shown in the drawing (FIG. 22), mortises 76 and 78,serving to attach bars 66 and 69 respectively, are preferably placed atdistances equal to the aforementioned P from mortises 75 and 77, servingto attach bars 65 and 68, which are then of identical thickness as bars66 and 69. Moreover, casings 80 of predetermined thickness 1',preferably brazed on one of the series of rods of the tool or stop, canbe inserted between the bars in such a way as to provide grooves 61 or63 (FIG. having widths greater than projections 47a and 62. This makesit possible to design an invention tool and stop by fastening betweenthis tool and stop, identical bars, said tool having a single inclinedramp 35 (FIG. 24) or two inclined ramps 35 and 35a (FIG. 23).

It should be further noted that it is advantageous (FIGS. 25 and 26) toreserve before ends forward of projections 47a, or before ends 65b, 66bof bars 65, 66, and behind the rear ends of projections 47a, or behindends 650, 66a of bars 65, 66, areas or surfaces 81, 82 located at adistance greater than P from projections 47a, i.e. behind with respectto bottom 290 of groove 61; the expressions before, behind, forward andrear" being referred to by the direction indicated by Arrow G. Thisfacilitates removal of portions of car tidges, jackets or tie rods tornfrom component 3,'from grooves 61 and rubbing of tool surface 81 againstthis component is avoided when bottom 290 of groove 61 cuts it. Thesesurfaces 81 and 82 may also be placed at the same distance from bottom29c of the grooves and also split into a single surface 81a enclosinggrooves 61 and projections 47a, tool face 29a being thus reduced tothese projections.

Similarly, on stop 31, it is advantageous to reserve an area 83, locatedat a distance greater than P from projections 62 i.e. behind withrespect to bottom 31a of grooves 63 and in the neighborhood of the endsof the groove farthest from the tool. This surface, whose function is tofacilitate removal from these grooves, sections of cartridges, jacket ortie rod cut from component 3 by tool 29, may extend along projections 62or stop grooves 63, face 31a of this stop being thus reduced to thebottom of grooves 63.

In the FIG. 25 embodiment, where tool and stop are rough-hewn byhammering as in the case of FIG. 17 areas 81, 82 and 83 may be preparedduring this hammering, the presence of these areas also having theadvantage of facilitating the machining of grooves 61 and 63.

Finally, it should be noted, that as mentioned above, it is convenientto use a tool made of blade-holder 38 and support 54 attached toblade-holder '38 by tenon and mortise, grooves 61 being made in thissupport. Grooves 63 may also be included in bushing 42 attached by tenonand mortise to bushing-holder 41, assembly of this bushing holder andbushing 42 making up stop 31, as mentioned above.

As seen in FIG. 24, for example, support 54 is equipped with tenon bars65, 66 of equal length and analogous to those of FIG. 22. Ends 65b, 66bof these bars form inclined stepped ramp 35, their ends 65a, 66a formingparallel ramp 35b. Casing 84, connected advantageously to support 54 bytenon and mortise designated by reference 84a, and screws 85, permitsimmobilization of bars 65 and 66, this assembly of bars, support 54,casing 84, and assembly of support 54 on tool-holder 38 by tenon andmortise, not referred to in the drawing, in order to avoid cluttering itneedlessly, being symmetrically arranged with respect to a predeterminedemplacement center 44. The result is, that ramp 35 can be replaced byparallel ramp 35b by placing, for example once cover (FIG. 19) andcarriage 36 have been disassembled by the handling device mentionedabove a threaded rod (not shown) in hole 540.

Moreover, it has been specified in the above description, that table 20or magazine 13 (FIGS. 3 and 4) are equipped with a feed device 21 of aknown type, serving to advance (Arrow F) component 3 of the combustibleelement a predetermined distance p.

This device (FIG. 27) may include, for example, a motor or motor reducer86, equipped with starting device 86a connected to governor 45 by linesshown schematically in dotted form and capable of turning, by means oftransmission device 87, comprising pinions 88 and chain 89, a shaft 90going through protective housing 11. Pinion 91 is mounted on shaft 90and works together with rack 22a (FIG. 28) attached to ram 22, this rambeing mounted to slide on loading table 20 (not shown), or on magazine13 (FIG. 27) by means of bearings 92. Furthermore, shaft 90 turns bymeans of gears 93, preferably consisting of pinions, wheel 94 havingfinger 95 in contact with electrical switch 96 connected to starter 86aof motor 86 by wires represented schematically by dotted lines.

It should be noted, that the assembly indicated by references 86-96consists of aforementioned motor unit 23, wheel 94, depending on choiceof devices 87, 93, and pinion 91 making a complete revolution when ram22 advances a distance p, due to the action of motor 86.

Moreover, it is possible by disconnecting governor 45 and switch 96 fromstarter 86a, to operate motor 86 and ram 22 manually. Therefore,component 3 can be fed (Arrow F) into magazine 13 until its front endtravels a distance p (FIGS. 4 and 8) past plane face 29a, the rear endof this component being in contact with ram 22.

Finally, even though direction of slide of the tool and hold-down plate(Arrows F and G) have been represented as horizontal in FIG. 4, thisdirection may also be vertical, as illustrated as a variant in FIG. 28.

In this Figure, shears 9 is attached to a horizontal portion 11a of theprotective housing, orifice 27 then being cut in body 9a of the shearsand no longer in bottom 26 of this shears. Moreover, sliding directionof tool 29 and hold-down plate 30 is vertical, as representedsymbolically by Arrows G and H.

Feed device 21 serves to feed component 3 (Arrow F) an aforementioneddistance p, but its design remains identical or very nearly the same asthat of FIG. 27 and it is possible, for example, according to theinvention, to mount a projection 47 having height P greater than p, onthe tool.

The various embodiments described above are in no way limiting and theirdesigns may be modified, as desired, without departing from the scope ofthe invention.

I claim:

1. Apparatus for shearing an irradiated combustible element intofragments and comprising a feed device to

1. Apparatus for shearing an irradiated combustible element intofragments and comprising a feed device to advance the element in stepsin and along a predetermined path, a fixed stop having a face on whichthe element can be supported, a hold-down plate movable in a directionnormal to said path to clamp the element to the stop, a tool movable insaid direction and having a first plane face adjacent to the hold-downplate, with edge shaped to form at at least one stepped ramp shearingedge contiguous to the plate, and a shearing tooth projection fixed withsaid tool and spaced ahead of said shearing edge in said direction, saidprojection having its free end substantially in the plane defined bysaid shearing edge, in movement in said direction, with the tool.
 2. Theapparatus of claim 1, wherein the tool has a second plane face spacedfrom said first plane face in said direction, at least one said shearingtooth projection having one end fixed to said second plane face, thefree end of said one projection and said first plane face beingessentially coplanar and spaced from said second plane face in adirection parallel with said path by a distance greater than that bywhich the feed device advances the element in one stEp.
 3. The apparatusof claim 2, said one end of said one tooth projection being housed in ahole in said second plane face of the tool, and means removably fixingsaid one end of the projection within the hole.
 4. The apparatus ofclaim 3, said one end of the projection and the hole being rectangularin transverse section said last-named means comprising a screw insertedin the tool and engaging the projection.
 5. The apparatus of claim 3,said one end of the projection and the hole being circular in transversesection, said one end of the projection having a press fit in the hole.6. The apparatus of claim 3, said one end of the projection beingtruncated and fitting a correspondingly-shaped hole in the tool, saidtruncated end having a reduced threaded extension, said last-named meanscomprising a nut threadedly engaging said extension.
 7. The apparatus ofclaim 2, said second plane face of the tool being pierced by at leasttwo holes situated in respective, spaced, parallel planes perpendicularto said direction of movement of the tool, and a plurality of shearingtooth projections each having one end detachably secured in a respectiveone of said holes.
 8. The apparatus of claim 7, said first plane face ofthe tool forming a single stepped ramp shearing edge, said holes in thesecond plane face of the tool being arranged in a row parallel to saidramp.
 9. The apparatus of claim 7, there being at least three holes insaid second plane face, said holes being arranged in staggered relationwith respect to said direction of movement of the tool, there being ashearing tooth projection secured in each said hole.
 10. The apparatusof claim 7, the ends of at least two shearing projections beingpositioned in respective recesses in the tool, a bar affixed to the toolto span said recesses and two screws threaded through holes in the barand having their ends engaging the projections within the respectiverecesses to immobilize said projections.
 11. The apparatus of claim 4,one end of said screw having a knob and a threaded section having apredetermined thread shank diameter threaded through a hole in the tool,the other end of said screw engaging the projection and beingcylindrical, and having a diameter less than the shank diameter of saidthreaded section.
 12. The apparatus of claim 2, said tool comprising ablade-holder rabbetted to form a shoulder between first and secondparallel surfaces offset in the direction of said path, a supportattached by mortise and tenon connection to said blade-holder, withinthe rabbett, said support having two parallel plane faces defining saidfirst and second plane faces respectively.
 13. The apparatus of claim 2the face of the stop on which the combustible element can be supported,having a notch coplanar with the path of movement of a tooth projectionattached to said second plane face of the tool.
 14. The apparatus ofclaim 2, the tool comprising a plurality of spaced projections definingbetween them grooves having a bottom spaced from the free ends of saidprojections by said distance, said stop having spaced projectionsdefining between them grooves, each groove of the stop being located toreceive a respective projection in movement of the tool, the projectionsand grooves of the tool forming at least one stepped ramp.
 15. Theapparatus of claim 1 said first plane face being formed with integralspaced parallel grooves, each contiguous pair of grooves definingbetween them, a projection extending parallel with said direction, saidprojections having ends normal to said first plane face and collectivelydefining at least one stepped ramp inclined with respect to saiddirection.
 16. The apparatus of claim 15, the ends of the grooves remotefrom said stepped ramp being rounded for cooperation with a recess inthe contiguous face of the hold-down plate.
 17. The apparatus of claim14, the tool comprising a housing, said projections on the tool beingformed by two series of barS attached to said housing, said bars havingdifferent thicknesses, whose difference is equal to said distance, theother ends of the bars forming said stepped ramp, said ramp beinginclined with respect to said direction of movement of the tool andhold-down plate.
 18. The apparatus of claim 14, said stop comprising ahousing, said projections on the stop being formed by two series of barshaving alternately different thicknesses, said difference being equal tosaid distance, the other ends of the bars extending the face of thestop.
 19. The apparatus of claim 17, the bars having only two sectionalsizes, alternate ones having a thickness and width smaller and greater,respectively, than the thickness and width of the sectional size of theintermediate bars.
 20. The apparatus of claim 17, said bars being brazedto the housing.
 21. The apparatus of claim 17, said bars being ofordinary steel with the ends thereof of a material harder than ordinarysteel, said bars being attached to the housing by screws passing throughapertures in the bars.
 22. The apparatus of claim 14, said projectionscomprising two series of identical bars each having a tenon on one end,fitting a respective one of a first and second series of mortises in thetool, each bar of one series being disposed between a respective pair ofadjacent bars of the other series, the distance between said first andsecond series of mortises, measured parallel with said path, being equalto said distance.
 23. The apparatus of claim 14, said stop comprisingtwo series of identical bars each having a tenon on one end, each tenonfitting a respective one of two series of mortises in said stop, thedistance between the mortises of one series and the other series ofmortises being equal to said distance.
 24. The apparatus of claim 22,each tenon of each bar being immobilized in its mortise by set screws.25. The apparatus of claim 22, and linings of predetermined thicknessbrazed to one said series of bars of the tool and to one said series ofbars of the stop.
 26. The apparatus of claim 14, the tool having freeplanar areas located at the rear with respect to the bottom of saidgrooves, and bordering the ends of these grooves.
 27. The apparatus ofclaim 14, the tool having a free planar area located in the rear withrespect to the bottom of said grooves and surrounding these grooves andthe projections of the tool.
 28. The apparatus of claim 14, said stophaving a free planar area located at the rear with respect to the bottomof said grooves thereof and bordering the ends of these grooves farthestfrom the tool.
 29. The apparatus of claim 14, said tool comprising ablade-holder and a support assembled by mortise and tenon connection onthe blade-holder, said projections formed by and between the grooves ofthe tool being formed in said support.
 30. The apparatus of claim 14,said stop comprising a bushing-holder and a bushing fixed to thebushing-holder by mortise and tenon connection, said projections formedby and between said grooves of the stop being formed in said bushing.31. The apparatus of claim 29, said projections being tenoned bars ofidentical length, rigidly attached to the support the ends of said barsforming two parallel stepped ramps inclined in said direction, thesupport and bar assembly being symmetrical with respect to a center lineof the tool, parallel with said direction.
 32. The apparatus of claim31, said bars being fixed to the support by a lining assembled by tenonand mortise to the tool-holder, the support bars and lining assmblybeing symmetrical with respect to said center line.